Question 275827
(x+1)(x+3)(x+5)(x+7)=-15

Rearrange the terms

(x+1)x+7)(x+3)(x+5)=-15

(x^2+8x++7)(x^2+8x+15)=-15


Substitute x^2+8x with a

(a+7)(a+15)=-15

a^2+22a +120=-15

a^2+22a+120=0
a^2+12a+10a+120=0

a(a+12)+10(a+12)=0

(a+10(a+12)=0

REPLACE THE VALUE OF A WITH X^2 +8X
 and finish